I am using Calibre together with my Kobo Aura One since more than two years.

All of a sudden I am getting an error when transfering books to the reader. Here is the error message:
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calibre, version 3.37.0
FEHLER: Fehler: Fehler beim Kommunizieren mit dem Gerät

That error is because you have a book with a series name, but no series index. I would have said that was impossible. I'll fix the code to catch this and continue and get the fix in the next calibre release. In the meantime, you will need to find the book and set the series index.

Sorry, but, that is exactly the same error, and the answer is exactly the same. The only way that line can be giving that error is if the series index is somehow not set. I have no idea how that is possible.

I have put in a fix to handle this. This should be in the next release. If you cannot isolate the book that is causing the problem, you can turn of metadata updating in the driver configuration.

Turned the meta updating off and error disappeared. But as mentioned, the error appeared even when transfering books with no series entry.

The error is not happening when books are being sent. After that is done, calibre runs a second job that include the metadata update. But, it is doing the metadata update is for all books already on the device and in the device database. For all books on the device, it compares what is on the device to what is in the calibre library. If there are differences, it updates the device with what is in the library. To reach the line of code where the error is, there must be a difference in either the series name or index and the library has a series name. But, then there is no index.

For any books just sent, the metadata update is skipped as it is not in the database. And even if it was, the book state of the series info should mean it either can't get to that line, or it would have a series index. I'll have another look at this, but, I have sent plenty of books with and without series numbers in the last week without error.

Can you tell me what the "Metadata management" option is set to? This is on the "Sending books to device" page of the preferences. I usually recommend the automatic option for Kobo users as the other options means the collection management and metadata updating don't happen when the device is first connected. If it is one of the other options, it affects when the metadata update would be done, but, still shouldn't trigger this error.

Metadata handling was set to [Manual management]. I changed that to [Automatic management], turned "Read matadata from files on device" in Aura driver back ON, transferred a book and didn't get an error.

So: problem solved, thank you.

Note: I haven't changed anything, the set up was OK for more than two years.
But it seems to be OK again, and that's perfect.

Metadata handling was set to [Manual management]. I changed that to [Automatic management], turned "Read matadata from files on device" in Aura driver back ON, transferred a book and didn't get an error.

The "Read metadata from files on device" option wasn't what I was talking about. It was "Update metadata on the device" and it options.

Quote:

So: problem solved, thank you.

Note: I haven't changed anything, the set up was OK for more than two years.
But it seems to be OK again, and that's perfect.

The code where the error happens, has recently been completely rewritten. Along with a reasonable amount of the rest of the driver. Unfortunately, finding an error with no configuration changes isn't that surprising. Though, I still haven't worked out how it reach the code in the state to trigger the error.